NFL Notes: 49ers nose tackle Glenn Dorsey injured

San Francisco 49ers nose tackle Glenn Dorsey has a torn left biceps muscle and will undergo surgery, a person with knowledge of the injury said Saturday.

It's unclear how long he might be sidelined. Dorsey left Friday's practice with the injury. The source said Saturday that Dorsey had torn his biceps and would need an operation, speaking on condition of anonymity because the team had not announced anything about Dorsey's injury.

Losing Dorsey would be a huge blow 11 months after 2013 starting NT Ian Williams went down with a season-ending ankle injury in a Week 2 loss at Seattle. Dorsey quickly emerged as a reliable replacement and stabilizing force for the defensive line.

Quarterback talk

Johnny Manziel was back in his element: on campus, in a stadium on a Saturday. And on the field, Manziel may have tightened the competition to be Cleveland's starter.

The rookie QB showed off some of his dazzling and daring skills as the Browns scrimmaged at the University of Akron.

Manziel and Brian Hoyer took their battle into the public and in front of 20,673 fans, who didn't see much offensive scoring but got a chance to see Johnny Football make some plays with his legs and rocket arm.

Sam Bradford showed improved zip on the ball during the Rams' fan fest scrimmage. Bradford seems to be reaping the benefits of upper-body training while out with a knee injury. To keep Bradford's arm strong, the Rams are monitoring his "pitch count." … Drew Brees stood on the sideline throughout the Saints' first scrimmage of training camp, resting a strained abdominal.

Briefs

Rookie WR Kelvin Benjamin was back at practice for the Panthers and showed no lingering signs of a bone bruise in his left knee that kept him out for five days. … Dolphins QB Ryan Tannehill was effective during an intrasquad scrimmage, but the team got a scare when starting TE Charles Clay left the field early with a leg injury and did not return. … Chiefs DB Marcus Cooper tweaked his hamstring during practice.